This invention relates to a method of modifying the light reflecting properties of a glass surface comprising spraying such surface with an etching solution via a bank of spray nozzles. The invention extends to apparatus for performing such a method.
It is well known that when visible light is incident upon a transparent glass sheet, some of the light, in fact about 4%, is reflected at each of the glass/air interfaces, and there are instances where this specular reflection is very inconvenient. A well known example is the glass in picture frames. In cases where the illuminating light incident upon the glass emanates from a relatively bright source such as from a lamp or as direct sunlight, the specularly reflected light may be more intense than that reflected from the picture itself with the result that an image of the light source obscures the picture.
Specular reflection is also responsible for phenomena such as Newton's rings and other interference effects which are inconvenient in certain circumstances such as when viewing photographic diapositives sandwiched between sheets of glass or when viewing objects through double glazing units whose panes are not parallel.
Various proposals have been made for treating a glass surface with an etching solution in order to reduce or eliminate these interference phenomena, for example as described in Glaverbel's British Patent specification No. 1,151,931. There remains however a problem of reliably achieving a uniform modification of the glass surface, as is desirable for high quality products.